A truck driver involved in the highway crash that critically injured comedian Tracy Morgan and killed one of Morgan's colleagues is accused of vehicular homicide and not sleeping for 24 hours prior to the crash.

Kevin Roper, 35, of Jonesboro, Ga., is accused of slamming a Walmart big rig into Morgan’s limo bus early Saturday along the New Jersey Turnpike, police said. The crash killed one man on the limo bus and injured four others, including Morgan, 45.

Morgan’s longtime writing partner, James "Jimmy Mack" McNair, 62, died at the scene.

Roper allegedly "commit[ted] vehicular homicide by operating a vehicle recklessly and caus[ing] the death of James McNair, specifically by operating a 2011 Peterbilt Truck ... on the New Jersey turnpike without having slept for a period in excess of 24 hours resulting in a motor vehicle accident in violation of NJS 2C 11-51, a crime of the second degree," according to a criminal complaint from the Cranbury Township Municipal Court.

Roper was set to appear in court Wednesday to answer charges against him, according to the complaint. He was free today after posting $50,000 bond.

Morgan, Millea and Fuqua remained in critical condition this morning, a spokesperson for Robert Wood Johnson University Hospital told ABC News. In addition, Harris Stanton, another comedian, was treated and released.

Morgan, the former star of "Saturday Night Live" and "30 Rock," was recovering from a broken leg, femur, nose and several ribs. His rep, Lewis Kay, said Morgan was “more responsive” Sunday.

“We expect him to remain in the hospital for several weeks. His family is tremendously overwhelmed and appreciative of the outpouring of love and support from his fans,” Kay said.

The six-vehicle crash happened in the northbound lanes at mile marker 71.5 at around 1 a.m. Saturday, according to New Jersey State Police.

Roper turned himself in after the crash. Walmart has placed him on administrative leave and promised “to take full responsibility” if the accident was caused by the company’s driver.

In a statement issued late today, Walmart said: “With regards to news reports that suggest Mr. Roper was working for 24 hours, it is our belief that Mr. Roper was operating within the federal hours of service regulations. The details are the subject of the ongoing investigation and we are cooperating fully with the appropriate law enforcement agencies. The investigation is ongoing and unfortunately we can’t comment further on the specifics. Federal law requires drivers to work no more than 14 hours for any shift and 11 hours of driving.”

The driver of the limo bus said that after the crash, he heard Morgan screaming.

"I climbed around and heard Tracy screaming for help," said his driver, Tyrone Gale. "I climbed up on the body of the limo bus ... but I couldn't reach them."